1. Field of the Invention
The present invention relates to control of excitation interval of the coils of an electric motor.
2. Description of the Related Art
In a electric motor disclosed in WO2005/112230 A1, a drive signal of the electric motor is masked to reduce power consumption.
With this technology, the excitation interval of the drive signal is specified using an analog circuit which employs resistance. A resultant problem is that in the event that the resistance value changes owing to temperature changes for example, there is an associated change of excitation interval as well. Also, there has been a desire to enhance electric power saving of the electric motor.